Manipulating Moire Devices via Heterostrain Control and Dynamic Driving of Lattice Vibrations

Lattice manipulations such as strain and acoustic waves have the potential to strongly influence the electronic properties of van der Waals devices and moires. Using heterostrain control, we demonstrate the stretching of moire superlattices beyond those achievable by twist control alone. We achieve this heterostrain by mechanically straining a graphene layer relative to its hexagonal boron nitride (hBN) substrate. The stretched moires are directly imaged with conductive atomic force microscopy and electronic measurements are performed simultaneously. We observe shifted superlattice resistance peaks and Landau fans in transport that are consistent with a stretched superlattice unit cell. Theoretically, the heterostrained graphene-hBN moire is expected to exhibit quasi 1D electronic behavior. Our heterostrain control techniques should be generalizable to other twisted heterostructures such as twisted bilayer graphene.

In addition to heterostrain control, I will also discuss our recent experiments in which we modulate graphene’s electrical properties through the use of electrically generated terahertz acoustic phonons.